LET’S CHEW ON BRUXISM

II° CONGRESSO NAZIONALE

GSIDGruppo di Studio Italiano

Disordini Craniomandibolari

ABSTRACT BOOK

MARINA DI CARRARA3/4 GIUGNO 2016

CENTRO CONGRESSI CARRARAFIERESala Marmoteca

Congress presentation

Over the recent years, bruxism has emerged as a phenomenon that is capable of jeopardizing the integrity of the stomatognathic structures (i.e., teeth, jaw muscles, temporomandibular joints) and the success of teeth- or implant-supported restorations. For this reason, there is a growing interest in studying the various bruxism activities. In particular, there have been many attempts to get a deeper insight into the etiology and pathophysiology of bruxism, with the aim to achieve a better definition of the best diagnostic and management strategies.

Past beliefs about the role of deviations in dental occlusion were wrong, and it is now accepted that bruxism does not have a peripheral etiology related to dental occlusion. Instead, it is a central phenomenon related with a combination of factors, with particular importance of psychological issues in the etiology of awake bruxism. As far as sleep-related bruxism is concerned, it has been shown part of sleep arousals, which are micro-awakenings occurring in the transition to lighter sleep stages. From a therapeutic viewpoint, the best available strategies aim to reduce the potential harmful consequences: a “multiple-P” approach (e.g., plates, pills, psychology, and physiotherapy) is the standard of reference.

Current concepts support the need for discriminating between the different motor phenomena grouped together under the umbrella term “bruxism”, namely jaw/teeth clenching and teeth grinding. Based on these premises, currently accepted guidelines require a bruxism measurement to achieve a definite diagnosis, in order to identify the anamnestic predictors as well as the clinical signs and symptoms associated with bruxism activities.

Within these premises, this dental meeting will be entirely based on an interactive debate between the speakers and the participants on various bruxism topics. During the event, Frank Lobbezoo and Daniele Manfredini will give a full-day course on the current evidence on bruxism and its applicability in the clinical setting. On the next day, other renowned speakers (Junia Serra-Negra, Fabio Carboncini, Maurizio Zilli) will introduce workshops on two clinically relevant topics (i.e., bruxism in children, bruxism and prosthetic treatment) to be commented interactively with the co-chairmen and the attendants. The ultimate goal is avoiding frontal lessons in favour of more productive communication platforms to close the gap between research findings and clinical practice on this very emerging phenomenon.

In short, this congress, under the marvelous natural framework of the white marble quarries, will be an unmissable event to get an updated report on the available scientific evidence on bruxism, with the ultimate aim to provide strategies for their integration in the everyday practice of dental clinicians.

Congress program

Day 1 – Friday June 3rd, 2016

Seminal course: EVIDENCE-BASED BRUXISM

9.00-10.15 Bruxism diagnosis and etiology (Frank Lobbezoo)

10.15-10.45 Interactive discussion: the challenge of differential diagnosis and etiology

10.45-11.15 Coffee break and poster exhibition

11.15-12.30 Bruxism diagnosis in the dental office (Daniele Manfredini)

12.30-13.00 Interactive discussion: is definite diagnosis possible at chairside?

Light Lunch

14.00-15.15 Bruxism management and clinical consequences (Frank Lobbezoo)

15.15-15.45 Interactive discussion: is bruxism a treatment-demanding disorder?

15.45-16.15 Coffee break and poster exhibition

16.15-17.30 Bruxism and pain: still an unsolved issue? (Daniele Manfredini)

17.30-18.00 Interactive discussion: the bruxism, pain, and psychosocial factors triangle in the dental clinics

Day 2 – Saturday June 4th, 2016

Workshop discussions: HOW TO GET DEEPER INTO…

Topic 1 – Bruxism in children

9.00-10.00 An overview of bruxism in the pediatric age (Junia Serra-Negra)

10.00-10.30 Interactive discussion and short communications: assessment and management of bruxism in the youngsters

10.30-11.00 Coffee break and poster award ceremony

Topic 2 – Bruxism and prosthetic treatment

11.00-12.00 Prosthodontic management of bruxism patients: concepts, rationale, and clinical cases (Fabio Carboncini, Maurizio Zilli)

12.00-12.30 Interactive discussion and short communications: management of tooth wear

Short communications schedule and interactive discussion slots

The concept of the congress is to challenge the audience to interact with the speakers. For that reason, six 30-min slots have been reserved to interactive discussion, moderated by the main speakers in the main auditorium, during the two-day congress works. The schedule of short communications during the six slots is the following:

Slot 1 – Friday, June 3rd h10.15-10.45: the challenge of differential diagnosis and etiology

Milton Maluly - Polysomnographic study of the prevalence of sleep bruxism in a population sample of Sao Paulo (Brazil)

Slot 2 – Friday, June 3rd h12.30-13.00: is definite diagnosis possible at chairside?

Andrea Bargellini - Detection of sleep bruxism: comparison between an electromyographic and electrocardiographic portable holter and polysomnography

Alessandro Bracci - BruxApp: a novel smartphone device for the diagnosis and management of awake bruxism

Slot 3 – Friday, June 3rd h15.15-15.45: is bruxism a treatment-demanding disorder?

Federica Casasco - Sleep bruxism management: a comparison of the effects of two oral appliances

Eduardo Castrillon - Portable EMG devices, biofeedback, and contingent electrical stimulation uses in bruxism

Slot 4 – Friday, June 3rd h17.30-18.00: how to get deeper into the clinical assessment of the bruxism, pain, and psychosocial factors triangle

Beatrice Dal Borgo - Does asymmetry in the stomatognathic system correlate with body posture impairments? A systematic review

Ricardo Dias - Comparison between conventional and CAD/CAM occlusal appliances in the management of TMD and/or bruxism – results of a randomized controlled trial”

Slot 5 – Saturday, June 4th h10.00-10.30: assessment and management of bruxism in the youngsters

Joyce Duarte - Parents/caregivers’ report of sleep related bruxism in children: methodological analysis

Slot 6 – Saturday, June 4th h12.00-12.30: management of tooth wear

Piero Simeone - Lithium-disilicate full mouth rehabilitation of severe bruxism: a contemporary minimally invasive prosthetic approach

Fausto Sommovigo - When on earth should we put the mandible?

LECTURES

Bruxism: definition, (differential) diagnosis, epidemiology, and etiology – Frank Lobbezoo

Friday, June 3rd, h9.00-10.15

Bruxism is a popular topic: during the past years, several conferences fully dedicated to bruxism have been organized. However, only recently, consensus has been reached about its definition: bruxism is a repetitive jaw-muscle activity characterized by clenching or grinding of the teeth and/or by bracing or thrusting of the mandible. The activity can occur during sleep (sleep bruxism; SB) and during wakefulness (awake bruxism; AB) (Lobbezoo et al., 2013).

For its diagnosis, several techniques are available, viz., self-report (questionnaires, oral history), clinical examination, and instrumental techniques like electromyography and polysomnography (Lobbezoo et al., 2016). The likelihood that a bruxism diagnosis is valid, varies from possible (diagnosis based on self-report only) and probable (self-report plus clinical examination) to definite (self-report plus clinical examination plus instrumental techniques) (Lobbezoo et al., 2013). As part of the clinical examination, the assessment of tooth wear is indicated. Bruxism is thought to be the cause of mechanical wear due to dynamic tooth-to-tooth contacts, which is named “attrition”. The severity of attrition can be quantified by means of the recently developed Tooth Wear Evaluation System (TWES), a system by which tooth wear can be diagnosed (both qualitatively and quantitatively) and on the basis of which management-related decisions can be taken (Wetselaar & Lobbezoo, 2016). It is important to notice that assessing the occlusion and articulation in relation to bruxism is confined to the tooth wear phenomenon, because evidence is accumulating that there is no causal relationship between bruxism and “the bite” (Lobbezoo et al., 2012). Likewise, it is unlikely that bruxism causes damage to periodontal tissues (Manfredini et al., 2015a).

Bruxism as motor phenomenon can easily be confused with oral movement disorders like orofacial dyskinesia and oromandibular dystonia, which – when confined to the jaw – resemble tooth grinding and clenching, respectively (Lobbezoo, 2007; Lobbezoo & Naeije, 2007). This underlines the importance of a thorough oral history, which can reveal factors known to be associated with such movement disorders. When a dyskinesia or dystonia is suspected, proper referral to a neurologist is indicated. Similarly, also generalized movement disorders, such as Parkinson’s disease, can be characterized by focal manifestations in the orofacial area. Also in such cases, consultation with a neurologist is indicated and dental approaches (e.g., focused on the alleviation of possible consequences of the excessive movements like tooth wear or pain) should be guided by the outcome of such consultation.

Bruxism is a common phenomenon. While older work indicated a great variability in bruxism prevalence, from about 6% up to 90%, a recent systematic review has revealed more restricted prevalence ranges: 8-31% for “generic” bruxism (i.e., without a distinction between sleep and awake bruxism), 22-31% for AB, and 13±3% for SB in adults (Manfredini et al., 2013a). Notably, there are no differences between men and women, and the prevalence decreases with increasing age. In children and adolescents, high prevalences are found as well. For example, the prevalence

for SB varies from 3.5% to about 40% (Manfredini et al., 2013b). These rates are similar for boys and girls.

In the past, bruxism was thought to be causally related to morphological factors, like occlusion and articulation characteristics. As indicated above, this paradigm is now considered to be flawed. On the other hand, evidence is growing that biological, psychological, and exogenous factors are involved in the etiology of bruxism (Lobbezoo & Naeije, 2001; Lobbezoo et al., 2006). Amongst the biological factors, neurochemicals like dopamine and other neurotransmitters that play a role in motor control can be posted (Lobbezoo et al., 1996, 1997), along with genetic factors (Lobbezoo et al., 2014) and sleep-related factors (e.g., arousals) (van der Zaag et al., 2014). Stress, personality traits, and anxiety are examples of the psychosocial factors that play a role in bruxism (Manfredini & Lobbezoo, 2009). Finally, aspects of life style belong to the category of the exogenous factors, like smoking, alcohol, caffeine, and certain illicit drugs (e.g., Ecstasy) (Lavigne et al., 1997; Rintakoski et al., 2010a, b). Also prescribed medication can sometimes be causally associated with bruxism, like certain antidepressant drugs (notably selective serotonin reuptake inhibitors, SSRIs) (Winocur et al., 2003). Clearly, management strategies should take the presence of such factors into account.

Bruxism: consequences and management – Frank Lobbezoo

Friday, June 3rd, h14.00-15.15

Bruxism is commonly considered the “villain” of dentistry. Amongst others, the condition is commonly associated with muscle hypertrophy; attrition, fracture/ failure of teeth, restorations, and even implants; sensitivity/ pain of teeth, muscles, and temporomandibular joints (TMJs); and TMJ disc displacements. Despite the common clinical notion that implants can fail in possible causal association with bruxism, a systematic assessment of the literature shows that bruxism can indeed cause mechanical complications with implant treatment, while biological complications due to bruxism are unlikely (Manfredini et al., 2014). Temporomandibular disorders (TMD) are also commonly associated with bruxism. Over the past decades, however, literature reviews have failed to demonstrate causal relationships between both conditions, especially when bruxism was diagnosed with a higher degree of validity (i.e., at the definite level) (Lobbezoo & Lavigne, 1997; Manfredini & Lobbezoo, 2010). In the latter cases, even inverse associations were observed: more bruxism activity was associated with less TMD symptoms. A specific TMD symptom is the TMJ disc displacement. It has been demonstrated in adolescents that awake bruxism is associated with the non-reducing phase of this condition – in other words: awake bruxers with displaced discs are prone to develop locking TMJs (Kalaykova et al., 2011).

As for the management of bruxism: in a systematic assessment of the literature, it was concluded about a decade ago that only a small proportion of the studies on the topic were designed appropriately as randomized clinical trials (Lobbezoo et al., 2008). Of those, especially the pharmacological strategies seem promising, although further efficacy and safety assessments are needed before any recommendations can be made. In a recent update of this review, especially

mandibular advancement devices were shown to be effective, along with medications like botulinum toxin, clonazepam, and clonidine, while also contingent electrical stimulation yields promising results (Manfredini et al., 2015b). Clearly, however, more research is still needed. In the absence of definite recommendations, clinicians are suggested to follow the “triple-P” approach: Plates (i.e., hard stabilization appliances; not soft splints or “over-the-counter” splints), Pep-talk (i.e., counselling), and Pills (i.e., medication, prescribed by specialists, and only when the other two “P’s” fail) (Lobbezoo et al., 2008).

In conclusion: bruxism (both sleep and awake) is a common condition, the diagnosis and (non-pharmacological) treatment of which can be performed by dentists in most of the cases. Sometimes, however, in more severe cases, the condition needs to be diagnosed with tools like polysomnography, possible differential diagnoses need to be excluded, and pharmacological treatment needs to be performed. In those cases, a multidisciplinary approach is indicated.

References

Kalaykova SI, Lobbezoo F, Naeije M. Anterior disc displacement with reduction and intermittent locking among adolescents. J Orofacial Pain 2011;25:153-160.

Lavigne GJ, Lobbezoo F, Rompré PH, Nielsen TA, Montplaisir JY. Cigarette smoking as a risk or exacerbating factor for restless legs syndrome and sleep bruxism. Sleep 1997;20:290-293.

Lobbezoo F, Soucy JP, Montplaisir JY, Lavigne GJ. Striatal D2 receptor binding in sleep bruxism: A controlled study with iodine-123-iodobenzamide and single photon emission computed tomography. J Dent Res 1996;75:1804-1810.

Lobbezoo F, Lavigne GJ. Do bruxism and temporomandibular disorders have a cause-and-effect relationship? J Orofacial Pain 1997;11:15-23.

Lobbezoo F, Lavigne GJ, Tanguay R, Montplaisir JY. The effect of the catecholamine precursor L-dopa on sleep bruxism: A controlled clinical trial. Movement Disorders 1997;12:73-78.

Lobbezoo F, Naeije M. Bruxism is mainly regulated centrally, not peripherally. J Oral Rehabil 2001;28:1085-1091.

Lobbezoo F, Zaag J van der, Naeije M. Bruxism: its multiple causes and its effects on dental implants. An updated review. J Oral Rehabil 2006;33:293-300.

Lobbezoo F. Taking up challenges at the interface of wear and tear. J Dent Res 2007;86:101-103.

Lobbezoo F, Naeije M. Dental implications of some common movement disorders: A concise review. Archs Oral Biol 2007;52:395-398.

Lobbezoo F, Zaag J van der, Selms MKA van, Hamburger HL, Naeije M. Principles for the management of bruxism. J Oral Rehabil 2008;35:509-523.

Lobbezoo F, Ahlberg J, Manfredini D, Winocur E. Are bruxism and the bite causally related? J Oral Rehabil 2012;39:489-501.

Lobbezoo F, Ahlberg J, Glaros AG, Kato T, Koyano K, Lavigne GJ, Leeuw R de, Manfredini D, Svensson P, Winocur E. Bruxism defined and graded: An international consensus. J Oral Rehabil 2013;40:2-4.

Lobbezoo F, Visscher CM, Ahlberg J, Manfredini D. Bruxism and genetics: A review of the literature. J Oral Rehabil 2014;41:709-714.

Lobbezoo F, Koyano K, Paesani DA, Manfredini D. Sleep bruxism: Diagnostic considerations. In: In: Kryger MH, Roth T, Dement WC, Eds. Principles and Practice of Sleep Medicine, 6th ed. Philadelphia, PA: Elsevier, 2016:1427-1434.

Manfredini D, Lobbezoo F. Role of psychosocial factors in the etiology of bruxism. J Orofacial Pain 2009;23:153-166.

Manfredini D, Lobbezoo F. Relationship between bruxism and temporomandibular disorders: A systematic review of literature from 1998 to 2008. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010;109:e26-e50.

Manfredini D, Winocur E, Guarda-Nardini L, Paesani D, Lobbezoo F. Epidemiology of bruxism in Adults. A systematic review of the literature. J Orofacial Pain 2013a;27:99-110.

Manfredini D, Restrepo C, Diaz-Serrano K, Winocur E, Lobbezoo F. Prevalence of sleep bruxism in children: A systematic review of the literature. J Oral Rehabil 2013b;40:631-642.

Manfredini D, Poggio C, Lobbezoo F. Is bruxism a risk factor for dental implants? A systematic review of the literature. Clin Implant Dent Relat Res 2014;16:460-469.

Manfredini D, Ahlberg J, Mura R, Lobbezoo F. Bruxism is unlikely to cause damage to the periodontium. Findings from a systematic literature assessment. J Periodontol 2015a;86:546-555.

Manfredini D, Ahlberg J, Winocur E, Lobbezoo F. Management of sleep bruxism in adults. A qualitative systematic literature review. J Oral Rehabil 2015b;42:862-874.

Rintakoski K, Ahlberg J, Hublin C, Lobbezoo F, Rose RJ, Murtomaa H, Kaprio J. Tobacco use and reported bruxism in young adults: A nationwide Finnish twin cohort study. Nicotine Tob Res 2010a;12:679-683.

Rintakoski K, Ahlberg J, Hublin C, Broms U, Madden P, Könönen M, Koskenvuo M, Lobbezoo F, Kaprio J. Bruxism is associated with nicotine dependence: A nationwide Finnish twin cohort study. Nicotine Tob Res 2010b;12:1254-1260.

Wetselaar P, Lobbezoo F. The Tooth Wear Evaluation System (TWES): A modular clinical guideline for the diagnosis and management planning of worn dentitions. J Oral Rehabil 2016;43:69-80.

Winocur E, Gavish A, Voikovitch M, Emodi-Perlman A, Eli I. Drugs and bruxism: a critical review. J Orofac Pain 2003;17:99-111.

Zaag J van der, Naeije M, Wicks DJ, Hamburger HL, Lobbezoo F. Time-linked occurrence of sleep bruxism, periodic limb movements, and EEG arousals in sleep bruxers and healthy controls. Clin Oral Invest 2014;18:507-513.

About the speaker

Prof. Dr. Frank Lobbezoo graduated cum laude as dentist in 1988 from the University of Utrecht (UU), The Netherlands. In 1992, he obtained his PhD degree from the UU, after which he worked for three years as a postdoctoral fellow at the University of Montreal in Quebec, Canada. As of September 1996, he works at the Academic Centre for Dentistry Amsterdam (ACTA), The Netherlands, where he was appointed as a full professor in 2005. In 2014, he was appointed as Chair of the Department of Oral Health Sciences and Vice-Dean of ACTA. Frank Lobbezoo is specialized in TMD/Orofacial Pain, Past President of the European Academy of Craniomandibular Disorders (EACD), and President of the International RDC/TMD Consortium, a Network of the International Association of Dental Research (IADR). Frank Lobbezoo authored more than 200 papers in the field of bruxism and temporomandibular disorders in journals indexed in the Medline database. He also co-authored several textbooks on the same topics.

Bruxism diagnosis in the dental office – Daniele Manfredini

Friday, June 3rd, h11.15-12.30

In a consensus effort of experts Lobbezoo et al.1 suggested a grading system for SB. For a “possible” diagnosis, a positive self-report or proxy (partner) report is sufficient. For a “probable” diagnosis, a clinical examination suggestive of sleep bruxism should be present as well, while for a “definite” diagnosis, a positive polysomnographic recording, preferably in combination with audio/video recordings and with bruxism outcome measures above a predefined threshold, is required on top of a positive self-report and clinical examination. For a definite diagnosis of awake bruxism, things are even more complicated, and the best available option is the so-called ecological momentary assessment (EMA), which requires on-time evaluation of the ongoing bruxism phenomena.

Of course, for the clinician approaching to the bruxist patient, relying on questionnaires and self-reported data is the easiest approach to gather info on bruxism at chairside. Questionnaires can be used to obtain information about the condition itself, on its possible causes and consequences (see Introduction) as well as on its possible comorbidities and differential diagnoses but, unfortunately, their use is associated with several disadvantage, such as the need to rely on the patient’s preconceived ideas and understanding oh “bruxism”.

A well-formulated oral history interview may overcome in part those shortcomings, especially as far as the possible modulation of the questions, which can be adapted to the individual patient’s knowledge and cognitive abilities. On the other hand, oral history itself lacks standardization and may be influenced by the clinicians’ ideas. In addition, a disadvantage of the use of questionnaires/ora history for the diagnosis of sleep bruxism is that about 80% of the bruxism episodes are free of grinding sounds.2 Consequently, due to unawareness, self-reports of the condition may be characterized by underscoring with respect to the standard reference for a definite sleep bruxism diagnosis.

At present, the only investigation reporting both polysomnographic and self-reported sleep bruxism diagnosis in a large sample showed that only less than half of the self-reported bruxers were actually confirmed by polysomnography.3 Further, sleep bruxism fluctuates over time,4 which further hampers the accuracy of self-reported sleep bruxism. Hence, questionnaires should be interpreted with caution, and preferably, they should be used in combination with other diagnostic tools.5

A clinical examination that assesses “probable” focuses on the extra-oral assessment of masticatory muscle hypertrophy (see above) as well as on the intra-oral assessment of hyperkeratosis (i.e., dental impressions in cheeks [“linea alba”], tongue [“indentations”] and/or lips), tooth wear, fracture/ failure of restorations/ implants, and signs like tooth mobility, pulp necrosis, and traumatic ulcers.6 Importantly, all those clinical features lack specificity in the assessment of bruxism and the derived diagnosis should be viewed as a probability diagnosis based on the combination of one or more clinical signs.

Notwithstanding that, the most critical challenges for the clinician are the detection of ongoing

bruxism, and the discrimination between the different motor activities featuring bruxism.

Based on these premises, home-recording measurement devices for sleep bruxism7,8 and on-time EMA for awake bruxism,9 possibly achieved by using recently introduced technological devices are an emerging need for clinical practitioners willing to approach a definite bruxism diagnosis at chairside.

References

1. Lobbezoo F, Ahlberg J, Glaros AG, et al. Bruxism defined and graded: an international consensus. J Oral Rehabil. 2013; 40: 2-4.

2. Lavigne GJ, Montplaisir JY. Bruxism. Epidemiology, diagnosis, pathophysiology, and pharmacology. In: Fricton JR, Dubner R, Eds. Orofacial Pain and Temporomandibular Disorders. New York, NY: Raven Press; 1995: 387-404.

3. Maluly M, Andersen ML, Dal-Fabbro C, et al. Poylsomnographic study of the prevalence of sleep bruxism in a population sample. J Dent Res. 2013; 92: 97S-103S.

4. Zaag J van der, Lobbezoo F, Visscher CM, et al. Time-variant nature of sleep bruxism outcome variables using ambulatory polysomnography: implications for recognition and therapy evaluation. J Oral Rehabil. 2008; 35: 577-584.

5. Koyano K, Tsukiyama Y, Ichiki R, et al. Assessment of bruxism in the clinic. J Oral Rehabil. 2008; 35: 495-508.

6. Manfredini D, Bucci MB, Sabattini VB, et al. Bruxism: overview of current knowledge and suggestions for dental implants planning. Cranio. 2011; 29: 304-312.

7. Castroflorio T, Bargellini A , Rossini G, Cugliari G , Deregibus A, Manfredini D. Agreement between clinical and portable EMG/ECG diagnoisis of sleep bruxism. J Oral Rehabil 2015; 42(10):759-64.

8. Castroflorio T, Deregibus A, Bargellini A, Debernardi C, Manfredini D. Detection of sleep bruxism: comparison between an electromyographic and electrocardiographic portable holter and polysomnography. J Oral Rehabil 2014; 41: 163-169.

9. Manfredini D, Bracci A, Djukic G. Bruxapp: the ecological momentary assessment of awake bruxism. Minerva Stomatologica 2016. [In press].

Bruxism and pain: still an unsolved issue? – Daniele Manfredini

Friday, June 3rd, h16.15-17.30

Over the years, several clinical studies have been performed to assess the potential clinical consequences of bruxism on the natural and restored dentition.1,2 Historically, bruxism has also been viewed as a potential cause of overload of the temporomandibular joint (TMJ) and the jaw muscles.3 The musculoskeletal pathologies affecting the TMJs, the masticatory muscles, and the related structures are by convenience grouped together under the term “temporomandibular disorders” (TMD).4 They have a multifactorial etiology, with a number of factors interacting at the

individual level to determine the symptoms’ onset in a manner that it is yet to be fully clarified.5 For instance, although bruxism is commonly considered the most detrimental among all the parafunctional activities of the stomatognathic system and a major risk factor for TMDs, there are still many unsolved issues concerning the actual causal relationship between the occurrence of TMD symptoms and bruxism.

Based on this observation, this chapter will briefly outline the main findings from the literature on the topic, identify some recommendations for the future studies on the argument, and will then try to grasp some implications for the clinical practitioners.

The literature…

Several works investigated the association between bruxism-related overload and the presence of TMD symptoms. At present, the most comprehensive systematic literature review dated back to only a few years ago,6 and found its rationale in the need to get deeper into the newest articles with respect to a previous review on the topic.7

The 2010 review by Manfredini & Lobbezoo6 allowed retrieving interesting findings, especially concerning the different results emerging from studies adopting different strategies to diagnose bruxism (i.e., self-reported/anamnestic bruxism [21 studies]; clinically-diagnosed bruxism [7 studies]; experimental investigations [7 studies]; tooth wear assessment [5 studies]; and polysomnography (PSG) [4 studies] or electromyography (EMG) [2 studies]).

In general, the findings were supportive of an association between self-reported/questionnaire-diagnosed bruxism and TMD symptoms, which were found to be associated in almost all the studies adopting such a strategy to “diagnose” bruxism,8,9 with minor exceptions.10 In the majority of self-reported bruxism papers, an association was found with myofascial pain or symptoms of muscle disorders, but many studies did not specify which TMD symptoms were investigated. It was also reported that myofascial pain patients seem to have more teeth contact than controls over a 24-hour period, thus suggesting that the teeth-contacting habit may represent a risk factor for the prolongation of pain.11

Findings of the studies adopting a clinically-based diagnosis of bruxism supported its association with myofascial pain,12,13 while some reports of an association with joint disorders have also been identified.14,15 Notwithstanding that, in most studies the results did not unequivocally support/reject the hypothesized association and, in general, comparison of findings was not possible between any of the studies due to adoption of highly variable criteria for patient inclusion and study design.

Experimental investigations did not help better clarifying the potential role of bruxism-like muscle activities as sources of myofascial and/or TMJ pain. Findings suggested that the effects of low levels of prolonged clenching (10% MVCF for 30-60 min) provoked a short-lasting feeling of pain, while grinding may cause a delayed-onset pain in the day following the exercise.16,17 In all studies, effects tended to disappear shortly after the exercises.

Studies adopting tooth wear as a proxy to indicate the presence of bruxism showed the absence of any association between anterior tooth wear and TMD symptoms, clearly suggesting that the presence of worn teeth is not related with TMD.18,19

As for investigations measuring muscle activities during sleep, the results are difficult to interpret, because some inconsistencies of findings were present even between the studies performed by the same group of researchers. In summary, the rhythmic masticatory muscles activity (RMMA) that constitute the typical pattern of activity recorded with PSG during a sleep bruxism episode was found to be associated with myofascial pain in one paper, whilst no association was detected in another paper, and a negative association, viz., subjects with pain exhibited less episodes of RMMA/hr with respect to subjects without pain, was described in two studies.20-23 Also, results from the only two studies on EMG-based recordings of bruxism activity are controversial.24,25

Based on the above, the review suggested that:

- Data on the relation between specific TMD signs and symptoms and the different bruxism-related motor activities, viz., clenching and grinding, could not be discussed due to the very low level of specificity that characterized the majority of investigations, which were mainly based on self-reported bruxism and TMD diagnosis. - Works on self-report or clinical bruxism diagnosis showed a positive association with TMD pain, but they were characterized by some potential bias and confounders at the diagnostic level. In particular, the adoption of pain as a criterion for bruxism diagnosis led to obvious problems of circular reasoning. - Anterior tooth wear is not a major risk factor for TMD. - Experimental, sustained jaw clenching may provoke acute muscle tenderness, but it is not shown to be sufficient as the unique initiating factor for the onset of chronic pain.

Such conclusions seem to be still actual, since the main investigations published later than 2010 drew the same suggestions. Indeed, contrasting results emerged from studies on PSG-based bruxism diagnosis, which showed no association with myofascial pain,26 with respect to studies adopting a self-reported approach to bruxism detection, which reported its association with TMD, and myofascial pain in particular.27-29 Again, only a minor exception to the self-reported bruxism-TMD association were found.30 Clinically-diagnosed bruxism was weakly associated with TMJ pain.31

In summary, the literature on the topic of bruxism and TMD seems to be equivocal, and not in clear support of either the presence or the absence of a cause-and-effect relationship between the two conditions.

…its shortcomings and the recommendations for the future…

The most plausible hypothesis to explain the inconclusive literature findings on the bruxism-TMD relationship is that different conditions have been often meshed together without a clear-cut distinction. There is now emerging evidence that sleep and awake bruxism have a different etiology as well as there are observations that clenching-type and grinding-type activities are different motor phenomena with potentially-different consequences in terms of muscle fatigue and joint stress.32-35 Thus, it is unlikely that the literature-based knowledge will improve, unless those issues (i.e., different circadian rhythm of bruxism activities; different bruxism-related motor phenomena; different TMD diagnoses) are properly addressed in the study design phases.

In particular, a recent paper suggested that, whilst there is consensus that quantitative measurements of bruxism-related EMG activity of jaw muscles by means of PSG or EMG recordings are the

reference approach to bruxism quantification, there may be concerns about the clinical validity of the currently adopted PSG cut-off values for sleep bruxism to identify subjects with TMD.36 So, in the attempt to put bruxism into correlation with the potential clinical consequences, such as TMD, it is recommendable that future studies differentiate the different patterns of EMG activity characterizing the different bruxism-related motor phenomena. Such an approach is fundamental to define appropriate cut-off ranges to discriminate the different types of clinically relevant SB.

Furthermore, a possible explanation for the contrasting literature findings and unclear role of PSG cut-offs to identify pathological consequences may be found in the literature on EMG adaptations to pain in the jaw muscles. As a general rule, muscle activity is reduced as to prevent further damage when pain is present;37,38 anyway, recent findings suggested that motor adaptations to pain are not always univocal in terms of reduced EMG activity of painful muscles.39,40 Based on that, it can be hypothesized that muscle pain provokes different motor adaptations that may influence the PSG/bruxism-TMD relationship depending, for instance, on the pain chronicity. For example, certain types of bruxism activities (e.g., prolonged, high intensity, isometric contractions such as in the case of mandible thrusting) may be plausible triggers for TMD pain, but they are likely to be detected as such only in the early stages of pain onset, before protective adaptations start to effectively reduce muscle activity. On the other hand, the contrasting findings between PSG and questionnaire-based studies in the field of the TMD-bruxism literature may even suggest that other approaches based on patients’ history and clinical assessment are potentially more useful than PSG to diagnose clinically relevant bruxism in TMD patients.41

Considering the contrasting literature findings and the above described shortcomings, the following question arises: Is the “old-fashioned” idea of bruxism as a risk factor for TMD justified? And, more importantly: How to retrieve any useful clinical implications from such a confusing literature?

…and the derived clinical implications: are bruxism activities causes of TMJ and jaw muscles’ overload?

In the attempt to gain a better insight into the issue, it is important for the clinical practitioner to distinguish between the different forms of bruxism, viz., jaw clenching and tooth grinding. Indeed, it seems reasonable to hypothesize that clenching-type bruxism, which is associated with psychological factors and is characterized by high-intensity isometric forces, is potentially more detrimental for the TMJ than grinding-like bruxism.42

The load applied to the joints depends on the biomechanical aspects of muscle activity, such as the intensity and the direction. Intensity is maximal when muscle contractions are exerted in isometric conditions, and jaw clenching is the only activity which is characterized by isometric contractions of the jaw muscles, since all the other functional and non-functional activities are characterized by non-isometric muscle contractions, which produce forces of a lower intensity. Force direction usually has an orthogonal and a tangent component with respect to the loaded surface, with pure orthogonal forces producing the highest pressure over the loaded surfaces. The concept of orthogonally-loaded surfaces is strictly related with the number of condylar degrees of freedom, which determine the force distribution over the joint surfaces during loading. During the clenching activity the jaw has no degrees of freedom, since it is forced in the same static position. From a biomechanical viewpoint, this means that the load forces are continuously applied over the same

condylar area, in contrast with the other non-functional activities, which are characterized by an instant-by-instant change of the area where the force is applied as a result of the jaw kinematics and degrees of freedom.42 As a consequence, whilst grinding movements are more likely related with tooth wear and delayed-onset muscle soreness (DOMS), jaw clenching is more likely a source of joint overload. On one hand, such an hypothesis could explain the absence of association between tooth wear and TMD symptoms. On the other hand, it could also explain the association between self-reported bruxism and TMD symptoms, since the former is likely to be more easily perceived by an individual in the case of clenching-type bruxism, both during wakefulness and at awakening.

Clinically, the cyclic repetition of static loads on the same area may determine signs of condylar “fatigue”, that is a progressive reduction of condylar tissues’ capability to bear loads without losing their integrity. Such phenomenon is well described in papers reporting the sequence of tissue changes and the loss of integrity at the cellular level in the TMJ cartilage under experimental static prolonged compressive loads.43,44 Thus, joint overload may be the primum movens for the onset of TMJ degeneration, with the onset of clinical signs such as disc displacement and progressive condylar remodeling. Damage could also affect the structures themselves that are responsible for producing the forces, viz., the jaw muscles, since the prolonged activation of the same motor units under isometric contractions may cause motoneurons stop firing due to metabolic exhaustion. On this purpose, the Cinderella theory for work-related muscle pain 45,46 lends support to the hypothesis that long lasting activation of masseter muscles, as in the case of jaw clenching, may lead to clinical signs such as muscle fatigue and pain. The controversy of the experimental literature on this topic may depend on the one hand on the objective difficulties to reproduce experimentally the time and force amount of muscle activation needed to determine symptoms onset in a healthy individual and, on the other hand, on the poorly specific PSG-based literature in terms of type of muscle contractions.

In the clinical setting, factors such as pain chronicity, psychosocial issues, and even facial morphology, which influence the force orientation and the condylar shape and dimensions, may play a role in determining the type and severity of symptoms. Based on this suggestion, individualized researches and case studies are strongly recommended to try getting deeper into the issue of the bruxism-TMD relationship. For instance, it was recently suggested that clenching-related symptoms affecting the TMJs (i.e., pain and clicking sounds) are more severe in subjects with extreme occlusal conditions, likely indicating a hyperdivergent facial pattern.47

Conclusions: the triangle bruxism, pain, and psychosocial factors

In conclusion, the study of the relationship between bruxism and TMD has depicted a complex picture, with several issues yet to be clarified before achieving a full understanding of its clinical relevance at the individual level.

The clinical practitioner must realize that the term bruxism is an umbrella, grouping together different phenomena.48 Indeed, bruxism can manifest itself with different motor activities that should be discriminated on the basis of their EMG features. For instance, concerning sleep bruxism, a recent paper proposed to adopt an EMG-based classification identifying sleep bruxers into three groups of prevalently phasic (which is tentatively arousal-related [RMMA], and is mostly exerted with grinding-like movements), prevalently tonic (which is tentatively represented by teeth

clenching/mandible bracing), and mixed.36 The former two activities, in particular, may have different clinical relevance, ranging from a protective role against episodes of sleep apnea to a negative role due to their possible consequences in terms of muscle fatigue, delayed onset soreness, and/or joint load.48

In order to improve the transfer process from the research to the clinical setting, clinical practitioners have to appraise more carefully the concept of TMD as biopsychosocial disorders,49 thus helping researchers changing the old-fashioned paradigms based on the role of dental occlusion.50 The proposed mechanism for the bruxism-TMD relationship at the individual level is that stress sensitivity and anxious personality traits may be responsible for those bruxism activities that may lead to TMD pain, which, in turn, is modulated by psychosocial factors (e.g., depression, anxiety, treatment-seeking behavior). Thus, within the boundaries of the biopsychosocial theory for TMD, the triangle of mutually interacting factors bruxism, pain, and psychosocial issues plays the most critical role in the clinics of TMD patients.51

References

1. Manfredini D, Poggio CE, Lobbezoo F. Is bruxism a risk factor for dental implants? A systematic review of the literature. Clin Implant Dent Relat Res 2012 Nov 13 [Epub Ahead of print]. 2. Abe S, Yamaguchi T, Rompré PH, De Grandmont P, Chen YJ, Lavigne GJ. Tooth wear in young subjects: a discriminator between sleep bruxers and controls? Int J Prosthodont 2009; 22: 342-50. 3. Manfredini D, Lobbezoo F. Bruxism and temporomandibular disorders. In: Manfredini (Ed). Current concepts on temporomandibular disorders. Berlin, Quintessence Publishing, 2010: 135-152. 4. De Leeuw R, Klasser G (Eds). American Academy of Orofacial Pain. Orofacial pain : Guidelines for assessment, diagnosis and management. 5th ed. Chicago, Ill, USA, Quintessence Publishing 2013. 5. Greene CS; American Association for Dental Research. Diagnosis and treatment of temporomandibular disorders: emergence of a new care guidelines statement. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010; 110: 137-9. 6. Manfredini D, Lobbezoo F. Relationship between bruxism and temporomandibular disorders: a systematic review of literature from 1998 to 2008. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2010; 109: e26-e50. 7. Lobbezoo F, Lavigne GJ. Do bruxism and temporomandibular disorders have a cause-and-effect relationship? J Orofac Pain 1997; 11: 15-23. 8. Ciancaglini R, Gherlone E, Radaelli G. The relationship of bruxism with craniofacial pain and symptoms from the masticatory system in the adult population. J Oral Rehabil 2001; 28: 842-8. 9. Johansson A, Unell L, Carlsson GE, Soderfeldt B, Halling A. Risk factors associated with symptoms of temporomandibular disorders in a population of 50- and 60-year-old subjects. J Oral Rehabil 2006; 33: 473-81. 10. Van der Meulen MJ, Lobbezoo F, Aartman IH, Naeije M. Self-reported oral parafunctions and pain intensity in temporomandibular disorder patients. J Orofac Pain 2006 ; 20 : 31-5. 11. Chen CY, Palla S, Erni S, Sieber M, Gallo LM. Nonfunctional tooth contact in healthy controls and patients with myogenous facial pain. J Orofac Pain 2007; 21: 185-93.

12. Manfredini D, Cantini E, Romagnoli M, Bosco M. Prevalence of bruxism in patients with different research diagnostic criteria for temporomandibular disorders (RDC/TMD) diagnoses. Cranio 2003; 21: 279-85. 13. Molina OF, Dos Santos Jr J, Nelson SJ, Nowlin T. A clinical study of specific signs and symptoms of CMD in bruxers classified by the degree of severity. Cranio 1999; 17: 268-79. 14. Yamada K, Hanada K, Fukui T, Satou Y, Ochi K, Hayashi T, Ito J. Condylar bony change and self-reported parafunctional habits in prospective orthognathic surgery patients with temporomandibular disorders. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2001; 92: 265-71. 15. Israel HA, Diamond B, Saed-Nejad F, Ratcliffe A. The relationship between parafunctional masticatory activity and arthroscopically diagnosed temporomandibular joint pathology. J Oral Maxillofac Surg 1999; 57:1034-9. 16. Svensson P, Burgaard A, Schlosser S. Fatigue and pain in human jaw muscles during a sustained, low-intensity clenching task. Arch Oral Biol 2001; 46: 773-7. 17. Arima T, Svensson P, Arendt-Nielsen L. Experimental grinding in healthy subjects: a model for post-exercise jaw muscle soreness. J Orofac Pain 1999; 13: 104-14. 18. Pergamalian A, Rudy TE, Zaki HS, Greco CM. The association between wear facets, bruxism, and severity of facial pain in patients with temporomandibular disorders. J Prosthet Dent 2003; 90: 194-200. 19. John MT, Frank H, Lobbezoo F, Drangsholt M, Dette KE. No association between incisal tooth wear and temporomandibular disorders. J Prosthet Dent 2002; 87: 197-203. 20. Rossetti LM, Pereira de Araujo Cdos R, Rossetti PH, Conti PC. Association between rhythmic masticatory muscle activity during sleep and masticatory myofascial pain: a polysomnographic study. J Orofac Pain 2008;22: 190-200. 21. Rossetti LM, Rossetti PH, Conti PC, de Araujo Cdos R. Association between sleep bruxism and temporomandibular disorders: a polysomnographic pilot study. Cranio 2008; 26: 16-24. 22. Romprè PH, Daigle-Landry D, Guitard F, Montplaisir JY, Lavigne GJ. Identification of a sleep bruxism subgroup with a higher risk of pain. J Dent Res 2007; 86: 837-42. 23. Camparis CM, Formigoni G, Teixeira MJ, Bittencourt LR, Tufik S, de Siqueira JT. Sleep bruxism and temporomandibular disorder: Clinical and polysomnographic evaluation. Arch Oral Biol 2006; 51: 721-8. 24. van Selms MK, Lobbezoo F, Visscher CM, Naeije M. Myofascial temporomandibular disorder pain, parafunctions and psychological stress. J Oral Rehabil 2008; 35: 45-52. 25. Baba K, Haketa T, Sasaki Y, Ohyama T, Clark GT. Association between masseter muscle activity levels recorded during sleep and signs and symptoms of temporomandibular disorders in healthy young adults. J Orofac Pain 2005; 19: 226-31. 26. Raphael KG, Sirois DA, Janal MN, Wigren PE, Dubrovsky B, Nemelivsky LV, Klausner JJ, Krieger AC, Lavigne GJ. Sleep bruxism and myofascial temporomandibular disorders. A laboratory-based polysomnographic investigation. J Am Dent Assoc 2012; 143: 1223-1231. 27. Fernandes G, Franco AL, Siqueira JT, goncalves DA, Camparis CM. Sleep bruxism increases the risk for painful temporomandibular disorder, depression and non-specific physical symptoms. J Oral Rehabil 2012; 39: 538-544. 28. Manfredini D, Winocur E, Guarda-Nardini L, Lobbezoo F. Self-reported bruxism and temporomandibular disorders: findings from two specialized centers. J Oral Rehabil 2012; 39: 319-325.

29. Michelotti A, Cioffi I, Festa P, Scala G, Farella M. Oral parafunctions as risk factors for diagnostic TMD subgroups. J Oral Rehabil 2010; 37: 157-162. 30. Van der Meulen MJ, Lobbezoo F, Aartman IH, Naeije M. Validity of the Oral Behaviours Checklist: correlations between OBC scores and intensity of facial pain. J Oral Rehabil 2013 Nov 26 [Epub ahead of print]. 31. Manfredini D, Peretta R, Guarda-Nardini L, Ferronato G. Predictive value of combined clinically diagnosed bruxism and occlusal features for TMJ pain. J Craniomandib Pract 2010; 28: 105-113. 32. Manfredini D, Lobbezoo F. Role of psychosocial factors in the etiology of bruxism. J Orofac Pain 2009; 23: 153-166. 33. Lavigne GJ, Huynh N, Kato T, Okura K, Adachi K, Yao D, Sessle BJ. Genesis of sleep bruxism : motor and autonomic-cardiac interactions. Arch Oral Biol 2007; 52 : 381-384. 34. Lobbezoo F, Ahlberg J, Manfredini D, Winocur E. Are bruxism and the bite causally related? J Oral Rehabil 2012; 39: 489-501. 35. Manfredini D, Fabbri A, Peretta R, Guarda-Nardini L, Lobbezoo F. Influence of psychological symptoms on home-recorded sleep-time masticatory muscle activity in healthy subjects. J Oral Rehabil 2011; 38: 902-11. 36. Manfredini D, Ahlberg J, Castroflorio T, Poggio CE, Guarda-Nardini L, Lobbezoo F. Accuracy and clinical validity of sleep bruxism diagnosis. A systematic literature review. J Oral Rehabil, submitted. 37. Lund JP, Donga R, Widmer CG, Stohler CS. The pain-adaptation model: a discussion on the relationship between chronic musculoskeletal pain and motor activity. Can J Physiol Pharmacol 1991; 69: 683-694. 38. Murray GM, Peck CC. Orofacial pain and jaw muscle activity: a new model. J Orofac Pain 2007; 21: 263-278. 39. Minami I, Akhter R, Albersen I, Burger C, Whittle T, Lobbezoo F, Peck CC, Murray GM. Masseter motor unit recruitment is altered in experimental jaw muscle pain. J Dent Res 2013; 92: 143-8. 40. Manfredini D, Cocilovo F, Stellini E, Favero L, Guarda-Nardini L. Surface electromyography findings in unilateral myofascial pain patients: comparison of painful vs non painful sides. Pain Med 2013; 14: 1848-1853. 41. Paesani DA, Lobbezoo F, Gelos C, Guarda-Nardini L, Ahlberg J, Manfredini D. Correlation between self-reported and clinically based diagnoses of bruxism in temporomandibular disorders patients. J Oral Rehabil 2013; 40: 803-9. 42. Peretta R, Manfredini D. Future perspectives in TMD pathophysiology. In: Manfredini D (Ed). Current concepts on temporomandibular disorders. Berlin, Quintessence Publishing 2010: 153-168. 43. Torzilli PA, Deng XH, Ramcharan M. Effect of compressive strain on cell viability in statically loaded articular cartilage. Biomechan Model Mechanobiol 2006; 5: 123–132. 44. Peeters EA, Oomens CW, Bouten CV, Bader DL, Baaijens FP. Mechanical and failure properties of single attached cells under compression. J Biomech 2005; 38:1685–1693. 45. Hagg GM. Static work loads and occupational myalgia – a new explanation. In: Anderson PA, Hobart DJ, Danoff JV (Eds). Electromyographical kinesiology. Amsterdam, Elsevier, 1991: 141-144.

46. Madeleine P. Functional adaptations in work-related pain conditions. In: Graven-Nielsen T, Arendt-Nielsen L, Mense S. Fundamentals of musculoskeletal pain. Seattle, IASP Press 2008: 401-416. 47. Manfredini D, Vano M, Peretta R, Guarda-Nardini L. Jaw clenching effects in relation to two extreme occlusal features: patterns of diagnoses in a TMD patient population. J Craniomand Sleep Pract 2014; 32: 45-50. 48. Lobbezoo F, Ahlberg J, Glaros A, Kato T, Koyano K, Lavigne GJ, de Leeuw R, Manfredini D, Svensson P, Winocur E. Bruxism Defined and Graded: an International Consensus. J Oral Rehabil 2013; 40:2-4. 49. Suvinen TI, Reade PC, Kemppainen P, Kononen M, Dworkin SF. Review of aetiological concepts of temporomandibular pain disorders: a biopsychosocial model for integration of physical disorder factors with psychological and psychosocial illness impact factors. Eur J Pain 2005; 9: 613-33. 50. Manfredini D. Integration of research into the clinical practice. In: Manfredini D (Ed). Current concepts on temporomandibular disorders. Quintessence Publishing 2010: 459-468. 51. Manfredini D. The triangle bruxism, pain, and psychosocial factors. PhD thesis, ACTA Amsterdam, 2011. About the speaker Prof. Dr. Daniele Manfredini received his DDS from the University of Pisa, Italy in 1999, a MSc in Occlusion and Craniomandibular Disorders in 2001 from the same University, and a PhD in Dentistry from the ACTA Amsterdam, The Netherlands, in 2011. On January 2014, the Italian Ministry of University and Research (MIUR) appointed him as Professor by scientific production at the age of 38. Since 2006, Daniele Manfredini has been Assistant Professor and coordinator of the research projects at the TMD Clinic, Department of Maxillofacial Surgery, University of Padova, Italy. Currently, he holds teachings in Prosthodontics and Temporomandibular Joint Physiopathology as well as in Gnathology and Bruxism at the School of Dentistry, University of Padova. Daniele Manfredini authored more than 130 papers in the field of bruxism and temporomandibular disorders in journals indexed in the Medline database. He also edited the book “Current concepts on temporomandibular disorders” (Quintessence Publishing, 2010), including contributions from 45 world-renowned experts, and co-authored several textbooks on the same topics.

An overview of bruxism in the pediatric age – Junia Serra-Negra

Saturday, June 4th, h 9.00-10.00

Bruxism is a parafunction characterized by grinding or clenching of teeth and may affect children or adults. The etiology is multifactorial. There is a great controversy in the literature to study the prevalence of bruxism among children. This divergence is a consequence of a lack of diagnostic standardization. Possible bruxism, probabile bruxism and define bruxism are importante concept in the study of the bruxism. Polysomnography is the gold standard for diagnosis of bruxism. However, reflections on child behavior during the exam and the cost of this examination deserve reflection. It is also the controversial concept that bruxism in children may be physiological or pathological. There are research developed in Brazil that address the prevalence of possible bruxism among children and adolescents. Epidemiological surveys of associated factors are also important to know is the infant universe. Emotional factors, sociodemographic, environmental and multidisciplinary partnerships are encouraged. The results of Brazilian research, developed by Prof. Serra-Negra supported the development of social projects and public health. The presented investigations have partnerships with different areas of science. The pedagogy, physiotherapy, speech terapy, psychology, nursing, dentistry and the different medical specialties are the consolidation of the importance of knowing the child's world. Educational programs for clarification of concepts with the scientific community and the lay community are part of the proposed projects. There is an emphasis on stimulating the community itself is responsible for your health.

About the speaker

Prof. Dr. Junia Serra-Negra, DDI, MSc, PhD in Pediatric Dentistry is currently Associate Professor at the Department of Pediatric Dentistry and Orthodontics, Universidade Federal de Minais Gerais, Brasil. She is also the Pediatric Dentistry Director of Graduate Program in Dentistry of the Universidade Federal de Minais Gerais. In 2016, she completed her Post-Doctoral stage at the School of Dentistry, University of Padova. Junia Serra-Negra authored more than 20 papers in journals indexed in the Medline database, focusing mainly on the theme of bruxism in children.

Prosthodontic management of bruxism patients: concepts, rationale, clinical cases – Fabio Carboncini, Maurizio Zilli

Saturday, June 4th, h11.30-12.30

Approaching the esthetic and functional rehabilitation of a patient with severe bruxism provides almost always an increase in the vertical dimension of occlusion (VDO). Such an increase may be more or less relevant, and establishing its correct amount in millimeters is not easy, due to the lack of objective reference parameters or instrumental techniques that are capable to identify and quantify the needed amount of VDO increase. In such conditions, which are characterized by the need to change the maximum intercupsidation position (MIP), the reference position should be the centric relation (CR). CR is repeatable and may be transferred to mounted casts. The fundamental pre-requisite to work with CR concepts is that the temporomandibular joint (TMJ) must be asymptomatic, since CR is not necessarily a physiological position, even if physiologically acceptable: this means that it allows functional adaptation over time, without any negative influence on the TMJ and the jaw muscles.

Rehabilitation planning in bruxers should take into account for the many prosthodontic risk factors (e.g., teeth with root canal treatments, pre-prosthetic restorations, crown/root ratio, number and size of the implants) that may be “exaggerated” by bruxism: thus, it is a compelling need that the clinician adopts cautionary approaches to protect the patient against the above risk factors and reduce the risk for prosthetic failures.

Once considered these fundamental premises, the restoration strategies for complex cases is a step-by-step procedure that starts with the identification of the prosthodontic position, goes on with a temporary phase managed with provisional restorations to verify the functional adaptation of the stomatognathci structures, and ends up in the manufacturing of the definitive restorations based on a simplified occlusal design.

About the speakers

Dr. Fabio Carboncini received his DDS degree from the University of Siena, Italy, in 1985. He has been Clinical Teacher at the Postgraduate Program in Periodontology of the same University during the years 2004-2011. He has been an active member of the Italian Academy of Prosthetic Dentistry (AIOP) since 2003. He has been the AIOP Incoming President during the years 2013-2014 and he is the current President for the years 2015-2016. He has lectured extensively on various prosthodontic and implant dentistry topics at national and international events. He also coauthored the recent book “Il bruxismo nella clinica odontoiatrica” (Quintessenza Edizioni, 2015).

Dr. Maurizio Zilli received his MD degree from the University of Trieste, Italy, in 1982. He is an active member of the Italian Society of Periodontology (SIdP) and the Italian Academy of Prosthetic Dentistry (AIOP). He has been the AIOP Incoming President during the years 2009-2010 and President during the years 2011-2012. He has been also member of the AIOP Scientific Committee and currently serves within the Committee for the Evaluation and Acceptance of new Members. He is Visiting Professor at the Post-Graduate School of Oral Surgery, University of Trieste, Italy. He has lectured extensively on various periodontal and prosthodontics topics.

POSTER SESSION

Sleep bruxism management: a comparison of the effects of two oral appliances

Casasco F., Giacone M., Bargellini A., Castroflorio T., Deregibus A.

Gnathology Unit, Dental School, University of Turin, Turin, Italy

AIM: Sleep bruxism (SB) in a stereotyped movement characterized by grinding or clenching of the teeth during sleep, usually associated with an intense (excessive) arousal activity. It is the sleep-related motor disorder of primary interest for dental practitioners, considering several detrimental consequences on the stomatognathic system, including tooth wear, masticatory muscle tenderness and pain, headache and temporomandibular disorders. Based on that, a need emerged to define the best strategies to manage bruxism in the clinical settings. The aim of the study was to evaluate the therapeutic efficacy of two different oral appliances (OAs) (occlusal splint and functional orthopedic appliance) in reducing SB episodes and orofacial pain.

MATERIAL AND METHODOS: An expert clinician assessed the presence of SB based on the presence of one or more signs/symptoms (i.e. transient jaw muscle pain in the morning, muscle fatigue at awakening, presence of tooth wear, masseter hypertrophy), among patients referring to the Gnathology Unit of the Dental School (University of Turin). First screening recording with Bruxoff® device selected 22 SB patients.

Patients were assigned to two groups: occlusal-splint group (11 subjects: mean age 33.5 ± 13.76); functional

orthopedic appliance group (11 subjects: mean age 33 ± 13.34). Five (N=5) patients dropped out the study (three patients assigned to group treated with occlusal splint and two patients to group with functional orthopedic appliance) because of the complexity of the study, especially for Bruxoff recording.

Each subject was observed for six months consecutively (T0: screening, T1: 1 week, T2 : 1 month, T3 : 3 months, T4: 6 months) and monitored with a visual analogue scale. Furthermore, all participants nderwent

an instrumental recording at home with a portable device (Bruxoff®, OTBioelettronica, Torino, Italy) allowing a simultaneous recording of EMG signals from both the masseter muscles as well as heart frequency to evaluate variation on SB activity. Data were analyzed using Shapiro-Wilk test (for checking the normality), two-way Anova test (for analysis of variance) and test of multiple comparisons of Tukey-Siegel. All statistical procedures were performed with the software Statistical Package for the Social Science v. 23.0 (SPSS 23.0®, IBM, Milan, Italy). For each analysis a p-value<0.05 was set.

Results: Pain sensation significantly reduced both for stabilization splint and FGB groups (P < 0.001, 95% CI) after three months follow-up, with no differences between the two groups. SB episodes significantly reduced after three months only in FGB group (P < 0.001, 95% CI). Differences between FGB and stabilization splint groups were found at T4 period (P < 0.001, 95% CI).

Conclusion: This study showed that two particular kind of OAs could both reduce orofacial pain referred by the patients, but only the functional orthopedic appliance showed a statistical significant effect in reducing SB episodes. Further studies on larger and more representative samples, followed for a longer period are needed to obtain major information on SB management.

Parents/caregivers’ report of sleep related bruxism in children: methodological analysis. Joyce Duarte, Fernanda Morais Ferreira, Júnia Maria Serra-Negra, Saul Martins Paiva, Fabian Calixto Fraiz. Ortodontia e Disfunção Temporomandibular e Dor Orofacial, UFPR, Brasil Abstract Parents' report is the main method used for the study of sleep bruxism in children, especially in research involving large population groups. However, the lack of consensus and standardization of questionnaires can lead to response biases that difficult different studies comparisons. The aim of this research was to evaluate differences in the prevalence of reported bruxism when a general question was used and also a more detailed question, including the disorder frequency and time. This cross-sectional study was conducted with 201 parents/caregivers of children assisted in the pediatric dentistry clinics of Federal University of Paraná, Brazil. Data were gathered through three different questions applied in sequence. The baseline knowledge about bruxism was assessed by a previously tested question. Then, all participants received a standard explanation about the concept of bruxism, subsequently they answered to two more questions: “Does your child brux or has ever bruxed?" and “In the last 6 months, have you noticed your child making tooth-grinding sounds when s/he was sleeping for at least 3 to 5 nights per week?”. Descriptive and Chi square statistical analysis were performed with significance level set at 5%. The majority of participants were the children´s mothers (73%), the children’s mean age was 7.5 years (SD: 2.25) and 53% were male. The concept of the term "bruxism" was unknown to 52.23% of the sample. The answers to sections 2 and 3 presented statistical significant difference (P<0.001), and the overall prevalence of reported sleep bruxism were 30% and 26%, respectively. When the question included the disorder frequency and time, the prevalence of reported sleep bruxism was less than when a general question was used. This study demonstrated the need to standardize the questionnaires used to investigate parental report of sleep bruxism in children.

Assessment of coping and anxiety features in bruxers: a portable EMG/ECG study

Angela Arreghini, Daniele Manfredini, Alessandra Visentin, Silvia Cerea, Tommaso Castroflorio,

Luca Lombardo, Giuseppe Siciliani

Post-graduate School of Orthodontics, University of Ferrara, Ferrara, Italy

Objective To answer the clinical research question: “is there a correlation between any

psychological features and sleep bruxism (SB)?”

Methods Thirty-six healthy volunteers underwent an in-home evaluation with a portable device combining electromyography (EMG) and electrocardiography (ECG) recordings for SB diagnosis. They were administered questionnaires for state/trait anxiety levels and coping strategies.

Results Correlation analysis showed that SB index was not correlated with any of the psychological scales. Some significant correlations (r-values range from 0.393 to 0.458) emerged with items of the trait-anxiety and coping scales. Cross-tabulations of subjects with respect to the median (over-median vs under-median) scores for the various psychological measures retrieved significant correlations with SB for state-anxiety scores (Phi=0.456; p=0.006), trait-anxiety scores (Phi=0.369; p=.027), social support (Phi=0.387; p=0.020).

Conclusions Findings support the study hypothesis only in part and confirm the absence of clear-cut relationship between sleep bruxism and psyche.

BruxApp: a novel smartphone device for the diagnosis and management of awake bruxism

Alessandro Bracci, Goran Djukic, Alessandra Zani, Caterina Pandolfo, Edoardo Stellini, Daniele

Manfredini

School of Dentistry, University of Padova, Padova, Italy

BACKGROUND: Awake bruxism (AB) is a condition that could mirror some psychological disorders and could lead to several dental and medical consequences. Whilst its diagnosis should be preferably based on the so-called ecological momentary assessment (EMA) methodology, which enables an on-time report of the condition under study (e.g., jaw clenching, teeth contact, teeth grinding), the transfer process of such approach from the research to clinical setting has not been performed so far.

METHODS: Based on this premise, a smartphone app-based EMA for awake bruxism seems to be a very interesting strategy to introduce the advantages of EMA within the bruxism literature. Such an application, called BruxApp, is dedicated to the ecological momentary assessment of awake bruxism and its possible associated symptoms. BruxApp is based on a simple concept of data recording and has a very friendly graphic interface. The core idea behind the app is to send alert sounds that require an on time reaction and answer by the patient, who may thus acquire awareness of any bruxism-related habit. Such a strategy may also have interesting potential as a biofeedback technique to manage bruxism and its consequences.

CONCLUSIONS: The use of BruxApp may introduce several benefits both in the fields of bruxism research and in the clinical setting, where tailored management of such condition and its consequences is often hard to achieve.

BruxApp and the ecological momentary assessment of awake bruxism. Preliminary data on a sample of university students

Alessandro Bracci, Goran Djukic, Alessandra Zani, Caterina Pandolfo, Edoardo Stellini, Daniele Manfredini

School of Dentistry, University of Padova, Padova, Italy

AIM: To assess the prevalence of awake-bruxism related activities in a sample of university students by using a novel smartphone-based application (i.e., BruxApp).

METHODS: A sample of 25 students (14 Females; m.a. 24.2 years) attending the School of Dentistry, University of Padova, Italy, underwent an assessment of their wake-time bruxism activities. All participants downloaded an application for their smartphone, called BruxApp. They were instructed about how to use it and how to record the data drawn from the software’s graphical interface. In short, BruxApp send alert sounds at random hours during the day, and the individual has to answer on time about the current condition by tapping on one of the following display icons: relaxed jaw muscles; teeth contact; teeth clenching; teeth grinding; jaw clenching (without teeth contact). Data were recorded over a one week period.

RESULTS: On average, the prevalence of the above conditions over the seven-day observation period were as follows: relaxed jaw muscles, 65.3%; teeth contact, 19%; jaw clenching (without teeth contact), 11.8%; teeth clenching, 2.8%; teeth grinding, 0.2%. In general, there were no between-sex differences were shown, with p-values ranging from 0.067 to 0.748 (T-test).

CONCLUSIONS: BruxApp, a recently introduced application for smartphones, has confirmed its valuable potential as a strategy for the ecological momentary assessment of awake bruxism. Based on the seven-day observation period that is set by default, as an average, one-third of participants showed awake-bruxism related activities. This set of preliminary data could be enlarged in size and longitude to collect reliable estimates of awake bruxism prevalence.

Comparison between three treatment modalities for the management of myofascial pain of jaw muscles: preliminary data from a randomized controlled trial

Daniele Manfredini , Edoardo Stellini, Luca Guarda-Nardini

School of Dentistry, University of Padova, Padova, Italy

AIM: To compare the effectiveness of three treatment modalities for the management of myofascial pain of jaw muscles in a randomized controlled trial (RCT).

METHODS: Thirty (N=30) patients with a DC/TMD diagnosis of myofascial pain (mean age 35.3 yrs) and with a low pain-related impairment according to the Graded Chronic Pain Scale were recruited and randomly assigned to receive either lasertherapy (LST), oral appliance therapy (OA), or counseling (CSL). VAS pain levels as well as the Muscular Index (MI) of the Craniomandibular Index were adopted as outcome variables. Patients of the LST group underwent nine sessions of multiwave locked system (MLS®, ASA srl, Vicenza, Italy) laser application on the painful muscles over a three weeks period; patients undergoing OA treatment worn a flat occlusal appliance covering the maxillary teeth at night-time for three weeks, and then with intermittent use for the following two months; patients of the CLS group received advices on the symptoms and how to try self-managing them, with one reinforcement session per week over three weeks. Outcome variables were assessed at baseline, at three weeks, three months, and six months.

RESULTS: Only one patient belonging to the OA group dropped out of the study due to family problems. At baseline, after randomization, groups were matched for age and sex, and there were no differences as far as the outcome variables are concerned. ANOVA for repeated measures showed that the LST and OA groups achieved significant improvements in the MI after the three-week period (LST, p=.038; OA, p=.008), whilst VAS values decreased significantly only in the LST group (p=.018). At six months, improvement in the MI was maintained both in the LST (p=.025) and OA group (p<.001). As for VAS values, positive changes were still shown for LST (p=.001), and were retrieved also for the OA (p=.002) and CSL group (p=.048).

CONCLUSIONS: Findings of this RCT show that, despite differences in the short-term effectiveness of LST, OA with respect to CSL alone, all three treatment groups improved at six months. This may support a positive natural course of myofascial pain of jaw muscles in the absence of pain-related impairment, and may suggest that active treatments should be directed to maximize the positive changes in the short-term period.

Does asymmetry in the stomatognathic system correlate with body posture impairments? A

systematic review

Beatrice Dal Borgo, Giuseppe Perinetti, Luca Contardo

University of Trieste

ABSTRACT

Objectives. To assess the potential correlations between anatomical and functional asymmetry in the stomatognathic system and body posture impairments.

Methods. Literature search using the Medline, SCOPUS, LILACS and SciELO databases, the Cochrane Library and a manual search. Experimental and observational studies were included with no restrictions as to the type of asymmetry. Type of asymmetry, treatment and/or recording conditions, follow-up, postural examinations, main results and clinical implication were extracted, and risk of bias was assessed.

Results: Eleven articles (including 1 randomized clinical trial) were retrieved. The risk of bias was medium in 6 studies and high in the remaining investigations. Only 3 studies, all with high risk of bias and without follow-up, reported significant correlations between the asymmetry in the stomatognathic system and body posture impairments.

Discussion: According to the limited present evidence, asymmetry in the stomatognathic system does not appear to correlate with body posture impairments at a clinically relevant level.

Comparison between conventional and CAD/CAM occlusal appliances in the management of temporomandibular disorders (TMD) and/or bruxism – results of a randomized controlled trial.

Dias R, Fonseca J, Alves C, Messias A, Guerra F

Department of Dentistry, Faculty of Medicine, University of Coimbra , Portugal

Introduction: Occlusal appliances are used in the multidisciplinary management of temporomandibular disorders (TMD) and bruxism. Recently, it has been suggested that CAD/CAM devices may offer advantages to realize occlusal appliances.

Aim of the study: Compare the effectiveness of occlusal appliances obtained by CAD/CAM and

conventional methods.

Materials and methods: 24 patients (m.a.20 years, 16F, 8M) diagnosed with RDC/TMD and

Maciel questionnaire took part to a randomized controlled trial (RCT). Two occlusal appliances, one obtained by CAD/CAM and one by conventional methods, were built for each patient and adjusted at baseline. Randomization occurred after that, according to demand for treatment, 12 to CAD/CAM and 12 to conventional group. Follow-up appointments were made at 30, 90 and 180 days according to the IMMPACT recommendations. Occlusal evaluation was made with articular foils and T-Scan®.

Statistical analysis: Differences between groups were performed using Mann-Whitney U test.

Longitudinal group assessment was performed with Friedman test. Significance level set at P < .05.

Results: Generally, no significant differences were determined between groups. At baseline, better clinically relevant features were found for CAD/CAM appliances (lower thicknesses, greater passivity and comfort and lower oclusal adjustement time). During follow up time, patients with CAD/CAM appliances showed better clinical outcomes (TMJ sounds decrease, mandibular motion increase, pain reduction, lower somatization). 27,3% of patients rated their evolution as “much better” with CAD/CAM against 16,7% with conventional.

Conclusion: This comparative study showed similar effectiveness between CAD/CAM and conventional appliances. However, CAD/CAM presented some advantages and better clinical outcome for the patients. CAD/CAM is a potentially useful method to obtain occlusal appliances.

Comparison between subjective and objective occlusal evaluation methods – results of a clinical study

Dias R, Colaço C, Messias AL, Fonseca J, Guerra F., Nicolau P

Department of Dentistry, Faculty of Medicine of University of Coimbra

Objectives: Comparison between occlusal contacts obtained by the subjective method using articulating film, relatively to objective methods using computerized T- Scan® and ImageJ®

program.

Materials and Methods: Comparative clinical trial using different methods of occlusal contacts assessment over occlusal stabilization splint`s surface. Patients were placed in supine position and were asked to bite with maximum strength, in the maximum intercuspation position with 24μm articulating film between teeth and splint’s surface. An extra-oral photography was taken recording the splint`s surface with the obtained marks. Additionally, a computerized occlusal analysis was performed with T-Scan® III HD. A total of 2082 occlusal marks were analyzed and observed by an experienced clinician. Each mark was classified according to a predefined scale. The same marks were also analyzed with image analysis software ImageJ® (area and colorimetric intensity were recorded). The results were organized and subject to comparative statistical analysis.

Results: A correlation of r=0.476 (p> 0.01) was found between the area percentages obtained with ImageJ® and T-Scan®. Comparison of subjective and objective analysis methods resulted in a correlation of r=0.277 (p> 0.01) for T-Scan, and r=0.629 (p> 0.01) for the area percentage (ImageJ®).

Conclusions: A low correlation between objective and subjective methods of occlusal analysis commonly used was found. In this study, the introduction of a complementary objective analysis method (ImageJ®) consolidated the result of lack of correspondence.

Evaluation of condylar position by CBCT after static and dynamic registration in edentulous patients

Dias R, Veloso L, Messias AL, Fonseca J, Nicolau P

Department of Dentistry, Faculty of Medicine of University of Coimbra

Objectives: The aims of this study are: to compare the condylar position in articular fossa after static and dynamic registration; to analyse symmetry between right and left condyles and to examine the relationship between articular eminence and condylar position.

Methods: Twenty completely edentulous patients were included in this study. Static bite registration was obtained by chin guided manipulation and dynamic registration was performed by Gothic Arch Tracing. Patients were submitted to one CBCT for each method. Radiographic image measurements in lateral and frontal cuts were made. The distance between the condyle and glenoid fossa was measure in three distinct points (posterior/lateral, superior, anterior/medial). The images were superpositioned to guarantee that the measures were made in the same position/cut between the two methods.

Results: No statistically significant differences between the two methods were found. In dynamic registration all the distances between condyle and glenoid fossa were smaller, more consistent and equidistant. Condyles stayed in a closer position to the articular fossa and in a more “centred” position. For this bite registration method a higher symmetry between left and right condyle was found. Contrariwise static registration had a higher heterogeneity of results.

Conclusions: Dynamic bite registration seems a reliable and an accurate method to use. With the higher incidence of condylar symmetry and most equidistant position in articular fossa, it seems that this bite registration technique reproduces a favorable physiologic condylar position. More studies are necessary to validate this hipothesys.

A cone-beam computerized tomography assessment of the relationship between upper incisor inclination and articular eminence features in untreated patients with different facial type

Luca Lombardo , Niki Arveda ,Gabriella La Falce G, Alberto Del Giudice , Daniele Manfredini,

Giuseppe Siciliani

Post-graduate school of orthodontics, University of Ferrara, Ferrara, Italy

Objective: To verify the existence of any correlation between upper incisor inclination and articular eminence angle by means of cone-beam computed tomography (CBCT).

Materials and Methods: A sample composed of 60 untreated patients of age range 18-40 years, subdivided into groups based on facial type, was subjected to CBCT analysis via the following measurements: glenoid fossa size, articular eminence angle with respect to the SN plane and inclination of the axis and lingual surface of the upper central incisor with respect to the SN plane.

Results: Correlation analyses shows the existence of some relationships between the articular and incisal parameters in the overall sample. No statistically significant difference was found in the observed parameters between facial types, except for the angle between the incisal margin–cingulum and the SN plane, which was smaller in long with respect to short facial types.

Conclusions: There are no clinically relevant relationships between the features of the glenoid fossa and the incisor inclination in any of the three facial types.

Effects of clenching in TMD patients with different cranio-facial morphology

Lombardo L, Arveda N, Rossi A, Del Giudice A, Tonello E, Manfredini D, Siciliani G.

AIM OF THE STUDY. To asses if in a population of temporomandibular disorders (TMD) patients with clinically-diagnosed clenching-type bruxism, the patterns of TMD diagnoses are different in patients with different skeletal pattern (i.e., hypo- or hyper-divergent).

MATERIALS AND METHODS. The study sample consisted of 23 patients with bruxism habit, seeking treatment at the Department of Maxillofacial Surgery, University of Padova, who had routine lateral cephalograms. Signs and symptoms of TMD were assessed by a standardized clinical examination and the Temporomandibular Index (TMI). Patients were classified according with the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD, Axis I), supported by clinical findings and magnetic resonance imaging of the TMJs. Angular cephalometric measurements were taken to assess skeletal characteristics of the subjects.

RESULTS. Overall Temporomandibular Index and the Joint Index (JI) show a significant correlation with the gonial angle. Subjects with hyperdivergent facial profile were characterized by a higher prevalence of temporomandibular joint symptoms than patients with hypo-divergent profile.

CONCLUSIONS. In a population of TMD patients with clinically-diagnosed clenching-type bruxism, a relationship was shown between the opening of the gonial angle and the prevalence of TMJ symptoms, viz., the wider the gonial angle the higher the prevalence of TMJ symptoms. These findings may suggest that prolonged, clenching-related overload may have different effects in TMD patients with different facial morphology.

Polysomnographic study of the prevalence of sleep bruxism in a population sample of Sao

Paulo (Brazil)

Milton Maluly, Monica L. Andersen, Cibele Dal-Fabbro, Silverio Garbuio, Lia Bittencourt, José T.

T. de Siqueira, Sergio Tufik

Departamento de Psicobiologia, Universidade Federal de Sao Paulo, Sao Paulo, Brazil

Running title: Prevalence of sleep bruxism in an epidemiological study

Abstract

The goal of the current study was to estimate the prevalence of sleep bruxism (SB) in the general population of Sao Paulo (Brazil) using a representative sample of 1042 subjects who answered questionnaires and underwent PSG exams. We also determined the associations of SB (SB) with general social-demographic characteristics, sleep parameters, pain, sleep disturbances, anxiety and depression. The estimate of the prevalence was based on: 1) individuals who report SB in the questionnaires, 2) number of individuals that were diagnosed after having their electromyography of the masseter and temporal polysomnographic recordings analyzed. After polysomnography (PSG), the subjects were distributed into 3 groups: absence of SB, mild SB and moderate/severe SB. The results indicated that the prevalence of SB indicated by questionnaires and confirmed by PSG was 5.4%. Using PSG exclusively as criteria for diagnosis, the prevalence was 7.3% regardless of the SB complaints. Moreover, a 12.4% prevalence was found when we analyzed SB alone, regardless of the PSG. Of those 56 (5.4%) were sleep bruxers and 26 were classified as having low frequency SB, and 30 had high frequency of episodes. We observed higher motor activity in Phase 2 of sleep as well as a higher number of phasic episodes in all sleep phases. Vigil time subsequent to the onset of sleep was shorter in the SB group. A positive association was observed between SB and insomnia, higher degree of schooling, and normal/overweight BMI. No association was encountered between oral-facial pain and bruxism. These findings demonstrate the prevalence of SB in a population sample adopting PSG in conjunction with two questionnaires, and raise the evidence that a precise diagnosis of SB requires a detailed investigation of the complaints associated to an objective instrument of investigation.

Key-words: questionnaires, electromyography, anxiety, depression, insomnia, pain

Prevalence of awake bruxism activities in a sample of University students. Preliminary data from a longitudinal trial on three non-consecutive weeks

Daniele Manfredini, Angela Arreghini, Luca Lombardo, Filippo Schicchi, Giuseppe Siciliani

Post-graduate School of Orthodontics, University of Ferrara, Ferrara, Italy

AIM: The aim of the present study is to assess the prevalence of different awake bruxism activities by means of a dedicated software for smartphones (BruxApp) in a sample of University students and to evaluate if such prevalence varies over time, with regard to potentially stressful events.

MATERIALS AND METHODS : A sample of 13 volunteer University students (8 females and 5 males, mean age 28 yrs) attending the Post-graduate School of Orthodontics of the University of Ferrara, Italy, underwent monitoring of the awake bruxism activities over three non-consecutive weeks. The BruxApp software allows gathering on time information on the frequency of teeth clenching, jaw clenching, teeth grinding, and teeth contacts during wake time. The software was set to send 15 random alerts/day during the 9.00 am-8.00 pm time interval. The individual had to answer each alert by tapping on the display area indicating the current activity. To assess the longitudinal course of awake bruxism and the potential influence of a stressful event on its prevalence, three non-consecutive recording weeks were programmed: a baseline week (week 1), a stressful week preceding the examination the candidates had to perform at the end of the second post-graduate year (week 2), and a control week (week 3). A two-week wash-out interval was made between each recording period. Raw prevalence data on the awake bruxism activities were descripted as well as their possible changes over time (ANOVA test for significant differences between the three weeks).

RESULTS : Descriptive data showed that the majority of answers over the weeks were indicating a “relaxed” status with an average status(76.5% in the first week; 79.3% in the second week; 82.4 in the third week). Among the awake-bruxism activities, teeth contact(14.8% in the first week; 11.9% in the second week; 10.8% in the third week) and jaw clenching (12.4% in the first week; 11.5% in the second week; 5.6% in the third week) were the most prevalent. As for teeth clenching, prevalence was : 1.1% in the first week and was up to 6.9% in the third week. On the other hand, teeth grinding was reported in 1.9% of times in the first week and decreased to 0% during the following weeks. Despite some interesting trends were observed as far as the changes in prevalence are concerned, showing a progressive increase of relaxed answers and a decrease on teeth contact and jaw clenching habits and suggesting that a potential biofeedback effects is more important than the potentially stressful event, changes over time are not significant .

CONCLUSIONS : This study was the first research trying to gather real time data on the prevalence of awake bruxism and to monitor them over time, also with the introduction of a potentially stressful event (i.e., university exam) during the second recording week. Data suggest that teeth contact and jaw clenching habits are the most frequent awake bruxism activities. Their progressive reduction over time may be explained with several hypothesis (i.e., biofeedback effects; natural course; other external factors), but it suggests that introducing a stressful event per se is not enough to increase the prevalence of awake bruxism activities.

Detection of sleep bruxism: comparison between an electromyographic and electrocardiographic portable holter and polysomnography

Andrea Bargellini 1,2, Federica Casasco, Tommaso Castroflorio1, Daniele Manfredini2, Andrea Deregibus 1

1Department of Surgical Sciences, Specialization School of Orthodontics, Dental School, University of Torino, Italy

TMD Clinic, 2Department of Maxillofacial Surgery, University of Padova, Padova, Italy

Background: Recent polysomnographic studies showed that the sleep bruxism (SB) event is preceded by a sudden shift in autonomic cardiac activity. Therefore, heart rate could be the simplest-to-record parameter for use in addition to portable home-EMG monitoring to improve the accuracy in automatic detection of SB events.

Objectives: The aim of the study was to compare the detection of SB episodes by combined surface electromyography (sEMG) and heart rate (HR) recorded by a compact portable device (Bruxoff ®), with the scoring of SB episodes by a polysomnographic (PSG) recording.

Material and Methods: Twenty-five subjects (14 “probable” bruxers and 11 non-bruxers) were selected for the study. Each subject underwent the Bruxoff and the PSG recordings during the same night. Rhythmic masseter muscle activities (RMMA) were scored according to published criteria. Correlation coefficients and the Bland-Altman plots were calculated in order to measure the correlation and agreement between the two methods.

Results: Results showed a high correlation (Spearman correlation r=0.95, P<0.0001) and a high agreement (bias =0.05) between Bruxoff and the PSG. Furthermore, the Receiving Operator Characteristic (ROC) curve analysis showed a high sensitivity and specificity of the portable device (92.3% and 91.6% respectively) when the cut-off was set at 4 SB episodes per hour accordingly to published criteria.

Conclusion: The Bruxoff device showed a good diagnostic accuracy to differentiate RMMA from other oromotor activities. These findings are important in the light of the need for simple and reliable portable devices for the diagnosis of SB both in the clinical and research sett

Where on earth should we put the mandible? Occlusal and therapeutic strategies in prosthetic rehabilitations

Fausto Sommovigo

Private Practice, Viareggio, Italy

The literature as well as the clinical experience of leading prosthodontists suggest that there are different approaches to record the mandibular reference position for rehabilitation purposes. Centric Relation (CR) is, for most prosthodontists, the ideal reference position irrespective if the increasing of over-jet that may excessively change the anterior guide. Other clinicians refer to different approaches; just as an example, Slavicek considers the anterior repositioning of the mandible as a therapeutic position for patient with temporomandibular disorders (TMD), whilst Vailati and Belser in 2008 proposed the 3 step technique using M.I.P. as the starting point for full mouth rehabilitation.

Conversely, the possibility to change the vertical dimension of occlusion (VDO) for prosthetic needs has been universally accepted. The authors performed a review of the literature and their specific clinical experience to highlight the need for an evaluation of the more suitable mandibular anterior-posterior position between MIP and CR at the chosen VDO in order to obtain the best therapeutic result. The use of a semi-adjustable articulator with the upper cast mounted by face-bow technique and the lower split cast mounted either in R.C. and M.I.P. could be useful in the choice.

Portable EMG devices, Biofeedback and Contingent Electrical Stimulation applications in Bruxism

Eduardo Enrique Castrillon Watanabe

Section of Orofacial Pain and Jaw Function, Department of Dentistry, Aarhus University, Aarhus, Denmark; Scandinavian Center for Orofacial Neuroscience

Summary: Bruxism is a parafunctional activity, which involves the masticatory muscles and probably it is as old as human mankind. Different methods such as portable EMG devices have been proposed to diagnose and understand the pathophysiology of bruxism. Biofeedback / contingent electrical stimulation (CES) methods have been also studied lately in the field of bruxism as a management method. Results from studies on portable EMG devices that can assess EMG activity on multiple nights, tell us that it is possible to improve the accuracy of the clinical diagnosis of sleep bruxism. New algorithms and new devices have made it easier for the general practitioners to improve clinical diagnoses, but still the accuracy level does not reach the gold standard that uses the method of polysomnography. On the other hand awake bruxism diagnosis remains without an established gold standard method, and its characteristics make it complicated to assess bruxism using portable EMG devices. The possibility to assess bruxism like EMG activity on a portable device made it possible to use biofeedback and CES approaches in order to treat / manage bruxism. The available scientific information about CES effects on bruxism has shown some positive results decreasing EMG activity of the masticatory muscles. The available and more accessible technology is giving us the chance to improve our understanding of bruxism and its possibilities to manage / treat it. Therefore, it is expected a greater amount of novel research results due to the easier access to more precise and objective methods to assess bruxism.

Acknowledgements: The participation in this scientific event was possible due to the support of Aarhus University and Sunstar.

Lithium-disilicate full mouth rehabilitation of severe bruxism: a contemporary minimally invasive prosthetic approach

Piero Simeone

Private Practice, Roma, Italy

Background: Restorative treatment of severely worn dentition is typically indicated to replace deficient tooth structure, limit the advancement of tooth destruction, improve oral function and enhance the appearance of the teeth. Minimizing removal of additional tooth structure while also fulfilling the desire of patients to have higly esthetic restorations can present a prosthetic challenge when the existing tooth structure is already diminished, especially in the bruxers patients. In this particolar cases the restorations provide for a new masticatory pattern, according to the articular path and the muscolar activity.

Objective: The poster will be focused on the clinical and laboratory phases by using condylography, cephalometry and electromyography as diagnostic tools support. A comprehensive minimally invasive prosthetic treatment approach will be proposed, using a lithium disilicate all-ceramic material for the esthetic full mouth rehabilition in patient with severely worn dentition.

The Association Between The Circadian Cycle Profile And Bruxism: A Systematic Review

Junia Maria Serra-Negra;1 Carolina Castro Martins;1 Silvia Regolin;2 Edoardo Stellini;3 Frank Lobbezoo;4 Daniele Manfredini5

1 Associate Professor – Department of Pediatric Dentistry and Orthodontics, Federal University of Minas Gerais, Brazil

2 Undergraduate student – School of Dentistry, University of Padova, Italy 3 Full Professor and Head – School of Dentistry, University of Padova, Italy

4 Full Professor and Head – Dept. of Oral Kinesiology, ACTA, Amsterdam , The Netherlands 5 Associate Professor – School of Dentistry, University of Padova, Italy

Circadian rhythm is an endogenous regulator of the human biological clock. The light and dark cycle command the body's hormones. It can influence mood, metabolism and sleep quality. Some people have higher morning energy to perform their activities and are classified as Morningness. Others, on the contrary, have increased nocturnal activity, which classifies them as Eveningness. Studies show that when the human being can not respect your profile circadian cycle and carries out activities of its characteristics, your body work in stress. This stress can affect the quality of life and affect health. Bruxism is a parafunction characterized by grinding and / or clenching of teeth. This parafunction can affect children and adults. The etiology is multifactorial and strongly influenced by emotional factors. The aim of this systematic review is to analyze the publications that evaluated the association between profile of the circadian cycle and bruxism. indexed publications in the databases will be evaluated: Pubmed, Scopus, SciELO, Medline and Isi Web of Science. It will not be limited the year of publication. They will be evaluated studies whose participants are children or adults. The search strategy will take with the use of keywords: chronotype; circadian cycle; circadiam rhythm; bruxism, sleep bruxism; awake bruxism and tooth wear.

SI RINGRAZIA PER IL CONTRIBUTO NON CONDIZIONANTE